Abstract: A comparing unit 18, when a radio unit 1 receives a radio signal, compares an ambient noise level detected by a noise sensor 17 with a preset threshold value. If the ambient noise level is smaller than the threshold value, the comparing unit 18 outputs a set value signal SH, and sets a receiving voice level set value of a receiving voice level setting unit 19 to “SMALL”, a transmitting voice level set value of a transmitting voice level setting unit 20 to “LARGE” and a calling sound level set value of a calling sound level setting unit 22 to “SMALL”, respectively.

Abstract: A developing device used in an image forming apparatus has a developing roller at a lower opening of a toner hopper, and the developing roller contacts a photosensitive drum to form a developing portion therebetween. The hopper stores nonmagnetic toner and is provided with a toner stirring member and a toner feed roller being in press-contact with the developing roller in a lower part of the hopper. A doctor blade contacts a circumferential surface of the developing roller on an upstream side of the developing portion in a rotation direction of the drum. A conductive scooping sheet contacts the circumferential surface of the developing roller on a downstream side of the developing portion. A residual toner not used to develop a latent image on the drum and left on the developing roller is passed under the sheet into the hopper with the rotation of the developing roller.

Abstract: Two-color image forming apparatus has a bipolar photosensitive body, a first charging means, a first electrostatic latent image forming means, a first developing means, a second charging means, a second electrostatic latent image forming means, and a second developing means. The second charging means is a corona discharger having a corona ion stream control screen forming by laminating a conductive member with an insulating member and disposed at or near an open portion for radiating a corona ion.